Ebola vaccine shown to be ‘highly protective’ in big trial
New study in Guinea
involving a single shot
showed 100% efﬁcacy
BY

A RIANA E UNJUNG C HA

Scientists on Thursday announced a milestone in the fight
against Ebola, reporting that a
major trial of an experimental
vaccine shows that it may be
“highly protective” against the
virus, which has infected nearly
30,000 people and killed 11,000
worldwide since 2013.
Although the current outbreak
has been contained, health officials fear that the deadly pathogen could return and have been
racing to develop ways to stop it
should that scenario unfold.
The new study, led by the
World Health Organization, was

based in a coastal region of
Guinea known as Basse-Guinée.
The vaccine showed 100 percent
efficacy in protecting those who
got it. More than 11,800 people
participated in the trial.
“While these compelling results come too late for those who
lost their lives during West Africa’s Ebola epidemic, they show
that when the next Ebola outbreak hits, we will not be defenseless,” Marie-Paule Kieny, the
study’s lead author and WHO
assistant director general for
health systems, said in announcing the results.
When preliminary findings
were unveiled in July 2015, WHO
Director General Margaret Chan
called the vaccine a potential
“game-changer.”
Guinea was one of three West
African nations hit hardest by
Ebola beginning in 2014. Researchers are running two parallel studies of the same vaccine in

Sierra Leone and Liberia, the
other epicenter countries.
The vaccine used in the study,
known as rVSV-ZEBOV and licensed by Merck, involves just a
single shot. The U.S. Food and
Drug Administration and the
European Medicines Agency
have designated it for streamlined regulatory approval. A
number of other vaccines — developed by GlaxoSmithKline and
the Beijing Institute of Biotechnology, among other groups —
also have shown promise and are
advancing in human trials.
The Guinea trial, described in
the Lancet, used an approach
known as “ring vaccination,”
which the researchers described
as the same approach used to
eradicate smallpox. It involves
tracing all individuals who may
have been in contact with every
new person diagnosed with the
virus, from relatives who live in
the same household to visitors

and those who may have been in
close contact with the infected
person’s clothes or linens. In
some cases, contacts of contacts
also were considered to be at risk.
Ultimately, researchers identified 117 “rings,” or clusters of
people, for the study. Each was
made up of an average of 80
people.
At the beginning of the trial,
which took place in 2015, when
the virus was actively spreading
in the region, the rings were
randomly divided into two
groups. One was to get the vaccine immediately and the other
after a three-week delay. When
the first results showed that the
vaccine was working, everyone
was offered it immediately.
Those 18 and older got it initially,
then children older than 6.
The results were striking: In
the group of 5,837 people who
received the vaccine immediately, there were zero Ebola cas-

es. In the other group, which
included those who got a delayed
vaccination as well as those who
were never vaccinated, there
were 23 cases.
Kieny and research team
members from Guinea’s Health
Ministry and other international
partners also noted that vaccination appeared to create a type of
“herd immunity” that indirectly
protected people who had not
been vaccinated. But more research will be needed to confirm
this theory, they said.
Two serious adverse events
were reported after vaccination,
with one participant spiking a
fever and another suffering an
allergic reaction. Everyone else
either reported no side effects or
very mild ones such as headache,
fatigue and muscle pain. No
effects were long term.
Despite researchers’ caution
that more studies are needed to
confirm the vaccine’s safety for

children and other vulnerable
groups, such as individuals with
HIV, they are making plans to
accelerate its rollout should future trials further confirm safety
and effectiveness. Merck has
committed to having 300,000
emergency doses available soon
and to submit the licensing application to regulatory authorities by the end of 2017.
In a commentary piece — optimistically titled “First Ebola virus vaccine to protect human
beings?” — virologist Thomas
Geisbert of the University of
Texas wrote that the study data
was so strong that it seemed that
the vaccine “probably contributed to controlling the 2013–16
outbreak of Ebola virus disease
in Guinea.”
ariana.cha@washpost.com
More at washingtonpost.com/
news/health-environmentscience

U.S. population growth is lower than at any time since the Great Depression
BY

T ARA B AHRAMPOUR

Last year the United States had
the lowest rate of population
growth of any year since the Great
Depression, according to census
figures released Tuesday.
The milestone is largely the result of the aging of the population,
with more deaths last year than at
any time since 2000, according to
William Frey, a demographer and
senior fellow at the Brookings Institution.
The nation grew by 0.695 percent between 2015 and 2016 to
323.1 million, down from
0.732 percent the previous year —
the lowest increase since 19371938, when it was 0.6 percent.
Immigration also declined,
though for the past three years it
has been higher than it had been
since before the recession of 20072009. But the fall in the natural
increase, from 4.07 to 3.84 per
1,000, reflecting fewer births and
more deaths, is the lead cause of

the slowdown — and the trend is
expected to continue, Frey said.
“The aging of the population is
the main thing,” he said. “We still
have a positive natural increase,
and there are other countries that
don’t have that” — such as Germany and Japan.
But in coming years the increase will continue to decline,
with serious policy implications,
he said. “We need to pay attention
to the dependent older population
who’s going to have to be taken
care of, through Social Security
and Medicare and general support
for them.”
At the same time, he cautioned
that the United States will need to
invest in immigrants who are
helping to shore up the younger
segment of the labor force.
The latest numbers show some
states being hit harder by population loss while others are on an
upswing — shifts that could affect
future statewide and national
elections.

Western and Southern states
such as Nevada, Arizona and Florida, which took big hits during and
after the recession, have been
growing recently, while states
with higher costs of living, including New York and California, and
Midwestern states such as Ohio
and Illinois, have experienced a
decline in growth as people have
moved away.
Migration out of California had
stagnated during the recession
and post-recession period, but
now the Golden State appears to
be losing more migrants to neighboring states, in a phenomenon
known as domestic outmigration,
Frey said. A similar pattern is occurring between New York and
Southeastern states.
Utah is now the fastest-growing
state — its population increased
2 percent to 3.1 million — while
North Dakota, the growth leader
in 2014-2015, fell to become the
15th-slowest-growing state as its
oil extraction economy withered.

Illinois leads the nation in population losses for the third year in a
row, with its largest domestic outmigration since 1990.
Texas had the highest numeric
gains, with growth in immigration, domestic migration and natural increase. Florida, which bled
population during and after the
recession, also ranks high because
of immigration and domestic migration. California and New York,
on the other hand, rank high on
immigration and natural increase
but are among the nation’s biggest
losers in terms of domestic migration, ranking 49th and 51st, respectively.
The District of Columbia registered its highest population count
since the 1970s, at 681,170 — an
upward trend that is expected to
continue.
The changes have important
implications for future elections.
Projecting current trends onto the
2020 Census, Frey calculated that
Texas would gain three electoral

college votes, Florida would gain
two, and Arizona, Colorado, North
Carolina and Oregon would gain
one each. Alabama, Illinois, Michigan, Minnesota, Ohio, Pennsylvania, Rhode Island and West Virginia would lose one apiece. Given
this November’s voting, the shifts
would result in Donald Trump
netting two additional electoral
college votes from Hillary Clinton.
The changes imply that a lot
more states could be competitive
in national elections. Typically the
Midwest and the Northeast have
voted for Democrats while Southern and Southwestern states have
voted for Republicans. But Barack
Obama won some traditionally
Republican states, and Trump
picked up some traditionally
Democratic ones.
As domestic migration continues, Republicans will no longer be
able to rely on wins in Southern
states, and Democrats will have to
play stronger defense in Northern
industrial areas that they once

took for granted, Frey said, adding,
“It’s kind of up for grabs right now.”
Outmigration from areas with
declining economies can create a
vicious cycle, said Philip Cohen, a
sociology professor at the University of Maryland. “When the good
prospects are elsewhere, people
with good prospects leave,” he
said, adding, “The middle of the
country is still hollowing out overall in the long term.”
And as states such as California
experience more outmigration,
immigrants from Mexico and Central America could increasingly
head directly to states such as
North Carolina and Iowa, where
there are jobs. Once they and their
children become citizens, this
could have electoral implications.
“In the small towns where immigrants are going, they can have
a big effect,” Cohen said.
tara.bahrampour@washpost.com
Scott Clement contributed to this
report.